Fluidized hydrocarbon conversion catalysts which contain crystalline aluminosilicates, principally faujasitic aluminosilicates (Type X and Type Y zeolites) have been commercially available for many years. These fluidized catalysts have been prepared by a variety of techniques in which the synthetic faujasite is prepared as a substantially pure compound and is then added to binding type materials such as silica or silica-alumina hydrogels. Clay or a mixture of clay and amorphous silica-alumina hydrogels may also be added in the preparation of these catalysts.
U.S. Pat. No. 3,867,308 to Elliott describes a process for preparing a hydrocarbon cracking catalyst in fluidized form by preparing an acid silica sol, adding clay and an acidified slurry of zeolite to the sol, spray drying before gellation occurs and washing the catalyst.
U.S. Pat. No. 2,384,946 to Marisic describes a method for preparing amorphous hydrogel particles which have catalytic cracking activity wherein a rapidly gelling silica hydrosol is sprayed into a fluid medium such as oil or air, and the sprayed sol particles gel or set to form particles of hydrogel.
U.S. Pat. No. 2,428,895 to Shoeld discloses a method for making silica-alumina gels wherein separate streams of alkali metal silicate and aluminum sulfate are mixed upon a rotating surface and the reaction product is centrifugally dispersed in the form of gel particles.
While the above noted Marisic and Shoeld patents disclose the preparation of amorphous hydrogel catalysts by the spray forming of rapidly gelling silica and/or alumina sols, these references do not disclose the preparation of catalysts which contain substantial quantities of zeolite and/or clay solids. The Elliott patent does not disclose a process wherein a rapidly gelling catalyst mixture is formed by spray atomization of a rapidly gelling mixture of acidic silica sol and basic zeolite slurry.